Electric tumbler switch



Jan.v 16, 1934. R BA|N r AL 3,943,363

ELECTRIC TUMBLER SWITCH Filed July 15, 1953 3 Sheets-Sheet l Jan. 16, 1934. R. BAIN El AL. 1,943,363

ELECTRIC TUMBLER SWITCH Filed July 15, 1933 5 Sheets-Sheet 2 HTTORNE] Jan. 16, 1934.

R. BAIN El AL ELECTRIC TUMBLER SWITCH Filed July 15, 1933 3 Sheets-Sheet 3 INVf-NTORSI @0551 r 677/! Nfwuz HLLDFIY QTTORIYCY Patented Jan. 16, 1934 UNITED STATES PATENT UFSFIQE ELECTRIC TUMBLER SWITCH Robert Bain, Handsworth, Birmingham, and Neville Allday, Four Oaks, England 20 Claims.

This invention relates to .electric switches of the kind in which a tumbler or pivoted operating member, moving in a plane substantiallyat right angles to the plane of the wall or support to which the switch is applied, operates a movable contact member moving in a plane substantially parallel to the plane of the wall or support.

The primary object of the invention is to pro- Vide a switch of relatively small depth from front to back thereof so that when applied to the surface of a wall or the like it projects therefrom only to a small extent or when adapted for'fiush fitting, can be accommodated in a relatively shallow recess, as for example, by recessing the plas- I ter facing of the wall.

The disadvantage of this construction, however, is that the parts of the switch are relatively close together, with a correspondingly increased danger of sparking or arcing between the live parts of the switch and other metal or conducting parts associated with the operating mechanism or exposed portions.

A further object is to provide means for reducing the possibility of such arcing or sparking.

Referring to the drawings:-

Figure 1 is a plan view of a switch constructed according to the present invention.

Figure 2 is a sectional end elevation of same recessed into a wall or other support.

Figure 3 is a sectional plan view.

Figure 4 is a section on the line 4-4 of Figure 1.

Figure 5 is a section on the line 5-5 of Figure 1 showing a switch mounted on a wall or other supporting surface.

Figure 6 is a detail view showing in perspective the movable contact member.

Figure '7 is a plan view partly in section of a modified construction according to the present invention.

Figure 8 is a sectional end elevation of same.

Figure 9 is a plan view showing the switch illustrated in Figure '7 with the operating mechanism of the switch in a slightly .diiferent position.

Figure 10 is a sectional elevation of the switch in the position illustrated in Figure 9.

Figure 11 is a detail perspective view showing a further modification.

Figure 12 is a plan view of same.

Figure 13 is a detail view showing a still further modification.

Figure 14 is a perspective view of a'detail modification.

Figure 15 is a perspective view showing a modified form of operating member.

In the construction illustrated in Figures 1 to 6 of the accompanying drawings the switch comprises a base 10 formed from porcelain or other suitable insulating material and provided with apertures 11 at each of the four corners, and with further apertures 12 disposed substantially at the centre of two opposite sides, as shown in Figure 3.

The stationary contacts 13 of usual construction and formed from strip metal are secured in two diagonallyopposite holes 11 by suitable securing bolts 14.

A movable contact 15 is operated by a tumbler or pivoted operatingmemberlfi mounted upon a pivot 17 in a housing 18, this housing being secured in position by a bridge piece 19 attached to the base by means of screws or bolts 20 engaging in the holes 12 in the base.

In the construction illustrated a one-way switch is provided and the movable contact 15, in the position illustrated in Figures 1 and 3, connects the stationary contacts 13, and in the other extreme position extends substantially in alignment with the holes 11 at which no stationar-y contacts are provided.

If, however, it is desired to provide a two-way or double circuit switch, stationary contacts '13 are provided at-each of the holes 11 and when the movable contact is moved out of the position such as shown in Figure 3, it engages with and connects a further pair of contacts 13 instead of moving into the Old position as is the case in the form of switch illustrated in the accompanying drawings.

.The movable contact 15 is formed from strip metal bent into the shape shown in Figure 6, having a .centralportion 21, located in a central recess 22 in the base 10, and having upstanding arms 23 and 24, the former being bent outwardly at 25 in a direction substantially parallel .to that of the portion 21, and being bent into substan tially inverted U form as .at 26, the outer portion 27 .forming the contact portion .to engage between the spring jaws of one of the stationary contacts 13.

The arm 24 is bent outwardly and downwardly, as shown in Figure 6, the downwardly projecting portion 28 forming the further contact portion to engage between the spring ,jaws of the remaining stationary contact 13.

The movable contact is pivoted upon .a pin .29 engaging in .a hole 30 in the base portion 21, and a further bearing for the pin 29 is provided by securing to the portion 25 a clip member 31 formed with a recess 32 in vertical alignment with the hole 30.

The pin 29 is, as shown in Figure 4, located in a recess 33 in the insulating base and in a further recess 34 in the insulating bridge portion 19.

The movable contact 15 is connected with the tumbler 16 by means of an intermediate link of telescopic form comprising a rod 35 engaging telescopically with a sleeve 36, the rod 35 having a forked end 37 engaging around a neck 38, at the inner end of the metal foundation of the tumbler 16.

The sleeve 36 is provided with an enlargement 39 of part spherical form engaging with a recess 40 in the arm 24 of the movable contact.

To insulate the operating members from the movable contact, an insulating washer41 is provided between the end 39 and the portion 24.

When the tumbler 16 is moved from the position shown in Figure 1, the rod .35 is telescoped into the sleeve 36 and a spring 42 provided around the link is compressed.

The intermediate link moves through an overdead-centre position with respect to the centre line of the movable contact 15, as the tumbler is moved from one to the other of its extreme positions, and when the dead-centre position is passed the movable contact is moved rapidly from the on to the off position, by the spring 42 which is compressed until the dead-centre position is reached,

In the construction illustrated in Figure 2, the switch is secured in a shallow box like casing 43 by means of screws or studs 44 and the switch is adapted for fitting flush with the outer so;- face 45 of the wall or support, which latter is recessed to accommodate the casing 43.

The switch and the casing 43 are secured to the wall by means of screws 49.

construction the recess required to enable such flush fitting need only be relatively shallow and the switch can be accommodated in a recess in the plaster facing of a wall, it being unnecessary to recess the brick work or masonry.

In the construction illustrated in Figure 5 the switch is applied directly to the surface 48 of a wall or other support by means of screws 49, but to simulate a flush fitting a shallow cover 50 is provided, this also being secured by means of a neck ring 4'7.

The cover 50 is of relatively shallow box like form with chamfered edges and projects only slightly from the surface of the wall or the like.

The covers 46 or 50 may be formed from mouldable material such as synthetic resin or the like and may be suitably finished.

In the constructions illustrated in Figures 7 to 10 the switch is provided with means for actuating the movable contact positively in the event 1 of the intermediate link failing or fracturing, and

the positive actuating means comprises an angle bracket secured to the tumbler 16, one arm 51 of this bracket engaging around and being secured to the shank 52 of the metal foundation of i the tumbler.

j and 10.

This arm 53 extends across part of the movable contact and the projections 54 extend one on either side of a tongue 55 pressed from the vertical inner limb of the end 26 of the movable contact, the portion 55 extending substantially parallel to the base portion 21 of the movable contact- When the tumbler 16 is moved from one to the other of its extreme positions, one or other of the projections engages with the tongue 55, as shown in Figure 9, so that in the event of failure of the intermediate link, the arm 53 will move the movable contact positively and the switch can be disconnected for repairs. The parts are arranged so that although one of the projections 54 may engage the pressed-out tongue prior to the operation of the over-dead-centre mechanism, the engagement is insufficient to turn the movable contact out of engagement with the stationary contacts.

As shown in Figure 9, the movable contact has been moved to a certain extent by the engagement between one of the projections 54 and tongue 55, but the intermediate link is in the dead-centre-position and slight movement from this position will allow the spring 42 to effect a rapid movement of the movable contact to prevent undue sparking.

In the modification illustrated in Figures 11 and 12 the rod 35 of the intermediate link is formed with an enlarged end 57 forked as at 58 for co-operation with the reduced end 38 of the tumbler, but the arms of the fork being spaced apart a greater distance than the diameter of the reduced end.

A wire stirrup 59 is provided in the forked end, the ends of the stirrup engaging in slots 60 as shown in Figure 12 and when the reduced end 38 engages in the stirrup 59 the latter pivots in the slots 50 as the tumbler 16 is moved and the operation of the switch is improved.

In Figure 13, is shown an alternative form of pivot for the movable contact, this comprising a tubular sleeve 61 riveted in the portion 21 of the movable contact, this tube engaging with the pivot pin 62 secured in the insulating base 10 and preventing tilting of the movable contact on the pm.

In this construction the pin 62 is riveted in the insulating base but if desired a pin as in Figure 4 may be guided at its upper end in a hole or recess formed in the insulating bridge 19 and, at its lower end in a recess in the base 10.

A pin 62 is provided as the pivot for the movable contact in the construction illustrated in Figures '7 to 10 where the operating member of the switch is provided with arms 52 and 53 extending one on either side of the pivot.

It is desired to support the upper end of the pivot pin in the construction illustrated in Figures '7 to 10 a strip or supporting piece may be provided across the bridge piece 19, this strip or supporting piece extending between the shank 52 and the arm 53 of the operating member.

As shown in Figures 1 to 3, Figures 4 and 5 and Figures 7 to 10, the insulating base 10 is provided with integral upstanding walls 63 extending between the operating mechanism and the stationary contacts, and in the construction illustrated, the walls are extended around the apertures 12 for the attachment of the bridge piece, as shown in Figures 1, 3, 7 and 9, so that the stationary contacts are separated entirely from the operating mechanism of the switch.

The inverted U shaped end portions of the movable contact extend over these upstanding wallsand the contact portions 27 and 28 each moves in a curved depression or recess 64 provided in the base on the outer side of the walls 63.

By this means the possibility of sparking between the stationary contacts and the operating mechanism of the switch is considerably reduced. This is of particular importance in a switch of the kind to which the present invention relates, since the reduction in the depth of the switch, namely, the distance from front to back, correspondingly reduces the distance between the operating mechanism and the stationary contacts or the liveportions of the switch.

Any sparking between the stationary contacts and the contact portions 27 and 28 of the mov able contact is confined outside the upstanding walls and drawn out along the curved recesses 64 and there is little possibility of the spark being transferred to the operating mechanism for the switch.

In order to prevent the possibility of sparking to the securing screws 49, which may be earthed or connected to earthed metal parts, upstanding walls 65 and 66 are provided one at each side of the base. The wall 66 is divided by means of a passage 67 which is utilized when it is desired to use the switch as a reversing switch and two pairs of interconnected stationary contacts are provided. The connecting wire is passed through the passage 6'? between the pair of stationary contacts on one side of the switch and is thus positively located in respect to and insulated from both the attachment screw for the switch and the movable contact.

In Figure 14 is illustrated a modification of the construction illustrated in Figures 11 and 12, the forked end 58 of the rod 35 being provided with a transverse wire or rod 68 in place of the stirrup 59. This wire is passed through holes drilled in the forked end.

In Figure 15 is shown a metal foundation for the tumbler 16, in place of the shank 52 and the positive actuating bracket 53. A strip of metal is formed at one end 69 to engage the tumbler 16 and is shaped at its other end 70, similarly to the arm 53 in Figures '7 to 10, including projections 54 to engage the movable contact.

A tongue 71 is pressed from the strip to engage with the forked end of the rod 35 and the strip is bent or pressed so that the tongue '71 and the end '70 extend in parellel relationship.

A bearing tube 72 is secured in the strip to engage the pivot pin for the tumbler and provide a good bearing surface for the tumbler 16.

What we claim then is:

1. An electric tumbler switch comprising an insulating base, stationary contacts mounted on said base, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting c the inner end of said tumbler and said movable contact, said movable contact being recessed centrally and said intermediate link being located in said central recess.

2. An electric tumbler switch comprising an insulating base, stationary contacts mounted on said base, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link engaging at one end with the inner end of said tumbler and at the other end with said movable contact, said movable contact being formed from strip metal with bent up ends, said intermediate link being located between said bent up ends and moving through an over-deadcentre position relative to the movable contact, when the tumbler is moved. a

3. An electric tumbler switch comprising an insulating base, stationary contacts mounted on said base, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable contact, a spring on said intermediate link, said movable contact being recessed centrally, said intermediate link being located in said central recess, moving through an over-dead-centre position relative to the movable contact, when the tumbler is moved, and said spring being com pressed until said over-dead-centre position is reached after which the spring imparts rapid movement to the movable contact.

4. An electric tumbler switch comprising an insulating base, stationary contacts mounted on said base, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable contact, said intermediate link being of telescopic form, comprising a rod engaging at its free end with the tumbler and a tubular extension telescoping on said rod, said tubular extension engaging at its free end with the movable contact, a spring on said intermediate link, said intermediate link moving through an over-deadcentre position relative to the movable contact, when the tumbler is moved and said spring being compressed until said over-dead-centre position is reached after which the spring imparts rapid movement to the movable contact.

5. An electric tumbler switch according to claim 4 having a part spherical end on said tubular extension, said part spherical end movably engaging said movable contact.

6. An electric tumbler switch comprising an insulating base, stationary contacts mounted on said base, a movable contact, a pivot on which said movable contact moves in a plane parallel tothe plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable contact, said intermediate link being of telescopic form, comprising a rod and a tubular extension telescoping on said rod, a forked end on said rod for engaging the tumbler, a part spherical end on said extension, said movable contact being formed from strip metal with bent up ends, and having an aperture in one of said bent up ends, said intermediate link being located between said bent up ends with said part spherical end engaging in said aperture, a spring on said intermediate link, said intermediate link moving through an over-dead-oentre position relative to the movable contact, when the tumbler is moved,

and said spring being compressed until said overdead-centre position is reached after which the spring imparts rapid movement to the movable contact.

'7. An electric tumbler switch comprising an insulating base, stationary contacts mounted on said base, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable contact, said intermediate link comprising a rod engaging at its free end with the tumbler, and a tubular extension telescoping on said rod, said tubular extension engaging at its free end with the movable contact, a spring on said intermediate link, said intermediate link moving through an over-dead-centre position relative to the movable contact, when the tumbler is moved, said spring being compressed until said over-deadcentre position is reached after which the spring imparts rapid movement to the movable contact, and projections on said tumbler to move said movable contact positively on failure of the intermediate link.

8. An electric tumbler switch comprising an insulating base, stationary contacts mounted on said base, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable contact, said intermediate link comprising a rod engaging at its free end with the tumbler and a tubular extension telescoping on said rod, said tubular extension engaging at its free end with the movable contact, a spring on said intermediate link, said intermediate link moving through an over-dead-centre position relative to the movable contact, when the tumbler is moved, said spring being compressed until said overdead-centre position is reached after which the spring imparts rapid movement to the movable contact, an arm on said tumbler, and projections on said arm engaging one on either side of said movable contact for positive engagement therewith on failure of the intermediate link.

9. An electric tumbler switch comprising an insulating base, stationary contacts mounted on said base, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler having two arms at its inner end, an intermediate link connecting one of said arms with the movable contact, projections on the other arm engaging one on either side of said movable contact, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, said intermediate link comprising a rod engaging at its free end with the tumbler, and a tubular extension telescoping on said rod, a part spherical end on said extension, said movable contact being formed from strip metal with bent up ends, and having an aperture in one of said bent up ends, said intermediate link being located between said bent up ends with said part spherical end engaging in said aperture, a spring on said intermediate link, said intermediate link moving through an over-dead-centre position relative to the movable contact, when the tumbler is moved, said spring being compressed until said over-dead-centre position is reached after which the spring imparts rapid movement to the movable contact, and said projections engaging said movable contact positively on failure of said intermediate link.

10. An electric tumbler switch comprising an insulating base, stationary contacts mounted on said base, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable contact, said movable contact being recessed centrally, said intermediate link being located in said central recess, upstanding walls on said base extending between said central recess and said stationary contacts, the ends of said movable contact extending over said walls to engage said stationary contacts, said intermediate link moving through an overhead-centre position relative to the movable contact, when the tumbler is moved, a spring on said intermediate link, and said spring being compressed until said over-dead-centre position is reached after which the spring imparts rapid movement to the movable contact.

11. An electric tumbler switch comprising an insulating base, stationary contacts mounted on said base, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable contact, said movable contact being formed from strip metal with bent up ends, said intermediate link being located between said bent up ends, up-

standing walls on said base extending between said bent up ends and said stationary contacts, said bent up ends extending over said walls and projecting downwardly on the outside of said walls to engage said stationary contacts, said intermediate link moving through an over-deadcentre position relative to the movable contact, when the tumbler is moved, a spring on said intermediate link, and said spring being compressed until said over-dead-centre position is reached after which the spring imparts rapid movement to the movable contact.

12. An electric tumbler switch comprising an insulating base, upstanding walls on said base, arcuate recesses in said base at the outer sides of said walls, stationary contacts mounted in said recesses, a movable contact, a pivot on which said movable contact moves in a plane parallel tOl the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable contact, said movable contact being formed from strip metal with bent up ends, said bent up ends extending over said walls and projecting downwardly on the outside of said walls to engage said stationary contacts, said downwardly projecting portions moving in said arcuate recesses, said intermediate link moving through an over-deadcentre position relative to the movable contact, when the tumbler is moved, a spring on said intermediate link, and said spring being compressed until said over-dead-centre position is reached after which the spring imparts rapid movement to the movable contact.

13. An electric tumbler switch comprising an insulating base, upstanding walls on said base, arcuate recesses in said base at the outer sides of said walls, stationary contacts mounted in said recesses, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable contact, said intermediate link comprising a rod engaging at its free end with the tumbler and a tubular extension telescoping on said rod, said tubular extension engaging at its free end with the movable contact, said movable contact being formed from strip metal with bent up ends, said bent up ends extending over said walls and projecting downwardly on the outside of said walls to engage said stationary contacts, said downwardly projecting portions moving in said arcuate recesses, said intermediate link moving through an over-dead-centre position relative to the movable contact, when the tumbler is moved, a spring on said intermediate link, and said spring being compressed until said over-dead-centre position is reached after which the spring imparts rapid movement to the movable contact.

14. An electric tumbler switch comprising an insulating base, upstanding walls on said base, arcuate recesses in said base at the outer sides of said walls, stationary contacts mounted in said recesses, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable contact, said intermediate link comprising a rod engaging at its free end with the tumbler and a tubular extension telescoping on said rod, said tubular extension engaging at its free end with the movable contact, said movable contact being formed from strip metal with bent up ends, said bent up ends extending over said walls and projecting downwardly on the outside of said walls to engage said stationary contacts, said downwardly projecting portions moving in said arcuate recesses, said intermediate link moving through an cver-dead-centre position relative to the movable contact, when the tumbler is moved, a spring on said intermediate link, said spring being compressed until said over-dead-centre position is reached after which the spring imparts rapid movement to the movable contact, and projections on said tumbler to move said movable contact positively on failure of the intermediate link.

15. An electric tumbler switch comprising an insulating base, upstanding walls on said base, arcuate recesses in said base at the outer sides of said walls, stationary contacts mounted in said recesses, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, having two arms at its inner end, an intermediate link connecting one of said arms with the movable contact, projections on the other arm engaging one on either side of said movable contact, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, said intermediate link comprising a rod engaging at its free end with the tumbler, and a tubular extension telescoping on said rod, said tubular extension engaging at its free end with the movable contact, said movable contact being formed from strip metal with bent up ends, said bent up ends extending over said walls and projecting downwardly on the outside of said walls to engage said stationary contacts, said downwardly projecting portions moving in said arcuate recesses, said intermediate link moving through an over-dead-centre position relative to the movable contact, when the tumbler is moved, spring on said intermediate link, said spring being compressed until said over-dead-centre position is reached aiter which the spring imparts rapid movement to the movable contact, and said projections engaging said movable contact positively on failure of said intermediate link.

16. An electric tumbler switch comprising an insulating base, stationary contacts mounted on said base, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable contact, said intermediate link comprising a rod, and a tubular extension telescoping on said rod, a forked end on said rod, a transverse wire across said fork, the inner end of said tumbler engaging said transverse wire, a part spherical end on said extension, said movable contact being formed from strip metal with bent up ends, and having an aperture in one of said bent up ends, said intermediate link being located between said bent up ends with said part spherical end engaging in said aperture, said intermediate link moving through an over-dead-centre position relative to the movable contact, when the tumbler is moved, a spring on said intermediate link, and said spring being compressed until said overdead-centre position is reached after which the spring imparts rapid movement to the movable contact.

17. An electric tumbler switch according to claim 16 having the ends of said transverse wire pivotally mounted in said forked end and the central portion of the wire being shaped to engage the end of the tumbler.

18. An electric tumbler switch comprising an insulating base, upstanding walls on said base, arcuate recesses in said base at the outer sides of said walls, stationary contacts mounted in said recesses, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler having two arms at its inner end, an intermediate link connecting one of said arms with the movable contact, projections on the other arm engaging one on either side of said movable contact, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, said intermediate link comprising a rod and a tubular extension telescoping on said rod, a forked end on said rod, a transverse wire across said fork, the inner end of said tumbler engaging said transverse wire. said tubular extension engaging at its free end with the movable contact, said movable contact being formed from strip metal with bent up ends, said bent up ends extending over said walls and projecting downwardly on the outside of said walls to engage said stationary contacts, said downwardly projecting portions moving in said arcuate recesses, said intermediate link moving through an over-dead-centre position relative to the movable contact, when the tumbler is moved, a spring on said intermediate link, said spring being compressed until said over-dead-centre position is reached after which the spring imparts rapid movement to the movable contact, and said projections engaging said movable contact positively on failure of said intermediate link.

19. An electric tumbler switch comprising an insulating base, upstanding walls on said base, arcuate recesses in said base at the outer sides of said walls, stationary contacts mounted in said recesses, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, a tumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable contact, said movable contact being formed from strip metal with bent up ends, said bent up ends extending over said walls and projecting downwardly on the outside of said walls to engage said stationary contacts, said downwardly projecting portions moving in said arcuate recesses, further upstanding walls on said base at the outer sides of said arcuate recesses, said intermediate link moving through an over-deadcentre position relative to the movable contact,

when the tumbler is moved, a spring on said intermediate link, and said spring being compressed until said over-dead-centre position is reached after which the spring imparts rapid movement to the movable contact.

20. An electric tumbler switch comprising an insulating base, upstanding walls on said base, arcuate recesses in said base at the outer sides of said walls, stationary contacts mounted in said recesses, a movable contact, a pivot on which said movable contact moves in a plane parallel to the plane of the base, atumbler, a pivot for said tumbler, a support for said pivot, said tumbler moving in a plane at right angles to the plane of the base, an intermediate link connecting the inner end of said tumbler and said movable con tact, said intermediate link comprising a rod and a tubular extension telescoping on said rod, a forked end on said rod for engaging the tumbler, a part spherical end on said extension, said part spherical end movably engaging said movable contact, a coiled spring disposed on said intermediate link between said forked end and said part spherical end, said movable contact being formed from strip metal with bent up ends, said bent up ends extending over said walls and projecting downwardly on the outside of said walls to engage said stationary contacts, said downwardly projecting portions moving in said arcuate recesses, said intermediate link moving through an over-dead-centre position relative to the movable contact, when the tumbler is moved, a spring on said intermediate link, and said spring being compressed until said over-dead centre position is reached after which the spring imparts rapid movement to the movable contact.

ROBERT BAIN. NEVILLE ALLDAY. 

